sql-server - 填补空白，基于事件

Question

我试图根据客户本可以完成的事件来计算客户流失，而不是按日期流失，这是正常的事情。我们有连接到特定主机的事件，在我的示例中，所有事件都由 Alice 托管，但它可能是不同的主机。

所有关注特定事件的人都应该归入一个类别(新的、活跃的、流失的和复活的)。

新品 :一个人第一次关注特定主持人的事件。
活跃 :再次关注(并且还关注了来自特定主机的最后一个事件)。
搅动 : 追随者有机会追随，​​但没有。
复活 :已流失的关注者已开始关注先前关注的主机。

declare @events table (event varchar(50), host varchar(50), date date)
declare @eventFollows table (event varchar(50), follower varchar(50))

insert into @events values ('e_1', 'Alice', GETDATE())
insert into @events values ('e_2', 'Alice', GETDATE())
insert into @events values ('e_3', 'Alice', GETDATE())
insert into @events values ('e_4', 'Alice', GETDATE())
insert into @events values ('e_5', 'Alice', GETDATE())

insert into @eventFollows values ('e_1', 'Bob') --new
insert into @eventFollows values ('e_2', 'Bob') --active
--Bob churned 
insert into @eventFollows values ('e_4', 'Megan') --new 
insert into @eventFollows values ('e_5', 'Bob') --resurrected
insert into @eventFollows values ('e_5', 'Megan') --active 

select * from @events
select * from @eventFollows

预期的结果应该是这样的

select 'e_1', 1 as New, 0 as resurrected, 0 as active, 0 as churned --First time Bob follows Alice event
union all
select 'e_2', 0 as New, 0 as resurrected, 1 as active, 0 as churned --Bob follows the next event that Alice host (considered as Active)
union all
select 'e_3', 0 as New, 0 as resurrected, 0 as active, 1 as churned --Bob churns since he does not follow the next event 
union all
select 'e_4', 1 as New, 0 as resurrected, 0 as active, 0 as churned --First time Megan follows Alice event
union all
select 'e_5', 0 as New, 1 as resurrected, 1 as active, 0 as churned --Second time (active) for Megan and Bob is resurrected

我从类似下面的查询开始，但问题是我没有得到关注者没有关注的所有事件(但可能已经关注)。

select a.event, follower, date, 
    LAG (a.event,1) over (partition by a.host, ma.follower order by date) as lag, 
    LEAD (a.event,1) over (partition by a.host, ma.follower order by date) as lead,
    LAG (a.event,1) over (partition by a.host order by date) as lagP, 
    LEAD (a.event,1) over (partition by a.host order by date) as leadP
from @events a left join @eventFollows ma on ma.event = a.event order by host, follower, date

有任何想法吗？

Answer 1

这可能看起来有点间接方法，但可以通过检查数字中的差距来检测岛屿:

;with nrsE as
(
    select *, ROW_NUMBER() over (order by event) rnrE from @events
), nrs as
(
    select  f.*,host, rnrE, ROW_NUMBER() over (partition by f.follower, e.host order by f.event ) rnrF
    from nrsE e
    join @eventFollows f on f.event = e.event
), f as
(
    select host, follower, min(rnrE) FirstE, max(rnrE) LastE, ROW_NUMBER() over (partition by follower, host order by rnrE - rnrF) SeqNr 
    from nrs
    group by host, follower, rnrE - rnrF --difference between rnr-Event and rnr-Follower to detect gaps
), stat as   --from the result above  on there are several options. this example uses getting a 'status' and pivoting on it
(
    select e.event, e.host, case when f.FirstE is null then 'No participants' when f.LastE = e.rnrE - 1 then 'Churned' when rnrE = f.FirstE then case when SeqNr = 1 then 'New' else 'Resurrected' end else 'Active' end Status
    from nrsE e
    left join f on e.rnrE between f.FirstE and f.LastE + 1 and e.host = f.host
)
select p.* from stat pivot(count(Status) for Status in ([New], [Resurrected], [Active],  [Churned])) p

最后 2 个步骤可以简化，但以这种方式获取“状态”可能可用于其他场景